Floor-type industrial vehicles, such as fork-lift trucks, are provided with steerable wheels in an axle assembly upon which the steering linkage is mounted and are required to have a relatively small turning radius to permit high maneuverability of the vehicle.
In prior art steering assemblies or linkages, the king pin angles require that the tie bar of the steering linkage be connected to the steering knuckle by ball joints to allow for the vertical movability of the tie bars during the steering operation.
For the most part, the knuckle was pivotally mounted above or below the axle body, usually below, while the hydraulic cylinder which controls the steering linkage was likewise displaced generally below this body and was connected pivotally to one axle carrier and to a location on the axle body or the vehicle frame or chassis at a location on the opposite side of the longitudinal vertical medium plane through the vehicle. This pivotal connection also generally required ball joints, especially when the hydraulic cylinder was pivotally connected to the vehicle frame or chassis to which the axle body was additionally affixed.
The numerous ball joints required in such systems had a tendency to deteriorate, and in general, maintenance was required to be frequent and was generally expensive.
Furthermore, the entire system was relatively large and frequently caused an unnecessary increase in the height of the vehicle chassis above the floor, limited the angular displacement of the steerable wheel and otherwise was less than satisfactory.